I is a bit older but she has had a persistent cough for 3 mths now. We have had her checked for asthma and although she seems to present symptoms when sick it actually isn't asthma yet - no wheezing between or any other symptoms. We are now just waiting on chest x-ray results to see if something else is going on. Having said that though she has a reliever puffer that we use 3 times a day and it does seem to help her. If it persists I would definitely keep getting him checked out as BW said it could be mild asthma presentation or the beginning of it. I had no idea a cough could signify it.